This invention relates to a flat key.
Known flat keys are cut on copying machines from a blank consisting of a shank or core which is milled on the machine in accordance with the profile of a specimen key, and of a head whose shape varies according to the lock manufacturer and which can be round, triangular, octogonal, rectangular, etc., this head comprising a hole for fastening the key to a ring, a key board or a hook. In general, lock manufacturers make their keys for one and the same type of lock with the same blank for the shank, although keys differing in the shape of their heads can be used for one and the same type of lock. Accordingly, manufacturers concerned with the production of replacement keys and specialising in copying keys from specimens presented to them are faced with the need to stock a large number of blanks in order to be able to reproduce the flat keys for every type of lock, this stock being further multiplied for commercial reasons by a certain number of decorative finishes for one and the same type of bland, namely nickel finishes, gold finishes or various coloured finishes. For example, if the locksmith has to keep a stock of "N" types of key to meet the requirements of his customers, he has to multiply this stock by "n" different decorative finishes.
Flat keys are already known which consist of two rigidly assembled parts, namely a shank having a head substantially equal in width to the shank, and an operating head which can assume any one of a number of external forms. The main advantage of manufacturing flat keys in this way is that it is possible for the operating heads to be made of an optionally castable material or of a material sufficiently soft to be able to receive impressions corresponding to the necessary references and marks or even decorative patterns (key heads in the form of medals, old or new coins, etc.), which gives rise to difficulties in the case of a key blank cut in one piece from sheet steel. In addition, it is possible, by making separate operating heads of plastics materials, to produce these heads in different colours.
In contrast, if as has hitherto been proposed, the keys have separate metal heads welded or crimped on to the shank, or plastics heads mounted on the end of the key blank, the shank or blank can only be assembled with the head in a factory and not by the locksmith or the key cutter who does not have the special machinery or equipment required. Accordingly, locksmiths and key cutters have to keep a large variety of blanks in stock. An object of this invention is to obviate this disadvantage.